Solid electrolytic capacitors are used in electronic circuits. For example, they are placed close to each power supply terminal of LSI devices and other integrated circuits.
A known solid electrolytic capacitor is made up of a capacitor element, an anode lead frame connected to the anode of the capacitor element, a cathode lead frame connected to the cathode of the capacitor element, and an exterior resin sealing the capacitor element. The anode lead frame and the cathode lead frame are partially exposed on the outside of the exterior resin.
For the purpose of reducing the equivalent series resistance (ESR) of such capacitors, the contact area between the capacitor element and cathode terminal lead frame is expanded. Specifically, at least one auxiliary cathode lead frame is connected to the capacitor element, and the auxiliary cathode lead frame and the cathode lead frame are interconnected (for example, see Japanese Laid-open Patent Publication No. 2004-247665).
However, a poor connection between the auxiliary cathode lead frame and the cathode lead frame may result from part size variations and vibrations generated at the time of manufacturing. In the worst case, the auxiliary cathode lead frame may have no connection with the cathode lead frame.
The lack of connection between the auxiliary cathode lead frame and the cathode lead frame results in an increased ESR and prevents desired electrical characteristics from being obtained. The two lead frames may only be jointed in a small contact area, if not completely separated. In this case, the connection resistance becomes larger, so the obtained ESR value may be larger than the desired value. Furthermore, if the auxiliary cathode lead frame is displaced from its normal position, the inner parts of the capacitor may be exposed from the exterior resin.